Final Analysis

The ST45SF is an honest product. Its performance is quite good given an affordable price tag. SFX-based power supplies tend to be expensive. But you can get this one for a little more than $65. If you're on a tight budget and you need a compact PSU, the ST45SF is one of your best options.

SilverStone is highly experienced in small form factor and high power density PSUs. The company avoids promising things it cannot deliver. For example, it is one of the few brands that doesn't over-commit on warranty coverage, offering up to five years on its high-end models. We respect this. Warranty periods in excess of five years look good on paper, but if components start going south, they end up hurting the companies servicing RMAs. While marketing can be a great tool, engineers have to keep those teams in check to keep them from going overboard. Take today's mining craziness, for example. Many companies are afraid because their long warranties don't take into account extreme duress. Most of a PSU's components won't even last three years delivering full power continuously at over 40°C ambient. Sales might be through the roof right now. However, returns can quickly gobble up profits months down the road.

The third version of SilverStone's ST45SF is equipped with a capable 92mm fan that maintains admirable acoustics under normal conditions. You shouldn't hear the fan working unless it's 20 or 30cm away from your ears. It's only when the loads get extreme that the fan makes its presence known. Even then, our readings just barely exceed 41 dB(A). We've measured much higher noise output under the same conditions from competing PSUs.

For us, the ST45SF's most notable downside is its low overall efficiency, attributable to the secondary side's passive rectification scheme. This platform combines new features with old design techniques (DC-DC converters mixed with double-forward topology and passive rectification) in an effort to keep manufacturing costs in check. The filtering caps aren't of high quality, either. But they'll survive SilverStone's warranty period.

The cooling fan uses an enhanced version of the popular sleeve bearing, so its lifetime shouldn't be a problem. All in all, the ST45SF is a pretty good deal for what you pay, and its performance per dollar score easily puts every other SFX power supply in our database to shame. If you can live with the native cables and your system doesn't consume 400-450W on a regular basis (200-300W is better), then this unit won't let you down. Get much above 400W, though, and efficiency will take a big hit.